Featured Research

from universities, journals, and other organizations

University Of Toronto Study Shows Marijuana Not A Factor In Driving Accidents

Date:

March 29, 1999

Source:

University Of Toronto

Summary:

The safety hazards of smoking marijuana and driving are overrated, says University of Toronto researcher Alison Smiley, whose study of impairment and traffic accident reports from several countries shows that marijuana taken alone in moderate amounts does not significantly increase a driver's risk of causing an accident.

Related Articles

Recent research into impairment and traffic accident reports from several countries shows that marijuana taken alone in moderate amounts does not significantly increase a driver's risk of causing an accident -- unlike alcohol, says Smiley, an adjunct professor in the department of mechanical and industrial engineering. While smoking marijuana does impair driving ability, it does not share alcohol's effect on judgment. Drivers on marijuana remain aware of their impairment, prompting them to slow down and drive more cautiously to compensate, she says.

"Both substances impair performance," Smiley says. "However, the more cautious behaviour of subjects who received marijuana decreases the drug's impact on performance. Their behaviour is more appropriate to their impairment, whereas subjects who received alcohol tend to drive in a more risky manner."

Smiley, who has studied transportation safety for over 25 years, drew her results from a "metanalysis" of existing research into the effects of marijuana on driving ability, combined with traffic accident statistics in the United States and Australia. Previous studies showing stronger effects often combined "fairly hefty doses" by researchers with driving immediately after consumption, likely exaggerating the drug's effects, she believes.

While Smiley does not advocate legalizing the drug, she says her results should be considered by those debating mandatory drug tests for users of transportation equipment such as truck or train drivers, or the decriminalization of marijuana for medical use. "There's an assumption that because marijuana is illegal, it must increase the risk of an accident. We should try to just stick to the facts."

Smiley presented her findings at a symposium of the American Academy of Forensic Sciences in Florida in February. Her paper was also published in Health Effects of Cannabis, a publication of Toronto's Centre for Addiction and Mental Health, in March.

University Of Toronto. "University Of Toronto Study Shows Marijuana Not A Factor In Driving Accidents." ScienceDaily. ScienceDaily, 29 March 1999. <www.sciencedaily.com/releases/1999/03/990325110700.htm>.

University Of Toronto. (1999, March 29). University Of Toronto Study Shows Marijuana Not A Factor In Driving Accidents. ScienceDaily. Retrieved March 31, 2015 from www.sciencedaily.com/releases/1999/03/990325110700.htm

University Of Toronto. "University Of Toronto Study Shows Marijuana Not A Factor In Driving Accidents." ScienceDaily. www.sciencedaily.com/releases/1999/03/990325110700.htm (accessed March 31, 2015).

Mar. 31, 2015  Increasing state alcohol taxes could prevent thousands of deaths a year from car crashes, say researchers, who found alcohol-related motor vehicle crashes decreased after taxes on beer, wine and ... full story

Mar. 31, 2015  Alcoholism takes a toll on every aspect of a person's life, including skin problems. Now, a new research report helps explain why this happens and what might be done to address it. "The clinical ... full story

Mar. 31, 2015  A new population of 'memory' immune cells has been discovered by scientists, throwing light on what the body does when it sees a microbe for the second time. This insight, and others like it, will ... full story

Mar. 31, 2015  Coronary heart disease and stroke, two of the leading causes of death in the United States, are diseases associated with heightened platelet reactivity. A new study in humans suggests an underlying ... full story

Mar. 31, 2015  A new study had researchers seeking answers to why the therapeutic benefit afforded by SSRIs was so limited in children and teenagers. If researchers can uncover the biological mechanisms preventing ... full story

Mar. 31, 2015  A drug being developed to treat osteoporosis may also be useful for treating osteogenesis imperfecta or brittle bone disease, a rare but potentially debilitating bone disorder that that is present ... full story

Mar. 31, 2015  It is possible to quantify and classify the effects of different diseases on the activity of intestinal bacteria, new research demonstrates for the first time. Human intestinal flora, known as ... full story

Mar. 31, 2015  During prenatal development, the brains of most animals, including humans, develop specifically male or female characteristics. But scientists have known little about the details of how this ... full story

Mar. 31, 2015  A history of depression may put women at risk for developing diabetes during pregnancy, according to research. This study also pointed to how common depression is during pregnancy and the need for ... full story

Featured Videos

Solitair Device Aims to Takes Guesswork out of Sun Safety

Reuters - Innovations Video Online (Mar. 31, 2015)  The Solitair device aims to take the confusion out of how much sunlight we should expose our skin to. Small enough to be worn as a tie or hair clip, it monitors the user&apos;s sun exposure by taking into account their skin pigment, location and schedule. Matthew Stock reports.
Video provided by Reuters

Soda, Salt and Sugar: The Next Generation of Taxes

Washington Post (Mar. 30, 2015)  Denisa Livingston, a health advocate for the Dinι Community Advocacy Alliance, and the Post&apos;s Abby Phillip discuss efforts around the country to make unhealthy food choices hurt your wallet as much as your waistline.
Video provided by Washington Post

S. Leone in New Anti-Ebola Lockdown

AFP (Mar. 28, 2015)  Sierra Leone imposed a three-day nationwide lockdown Friday for the second time in six months in a bid to prevent a resurgence of the deadly Ebola virus. Duration: 01:17
Video provided by AFP

Related Stories

June 5, 2014  The current state of science on the adverse health effects of marijuana use links the drug to several significant adverse effects including addiction, a review reports. The review describes the ... full story

May 15, 2014  The proportion of marijuana-positive drivers involved in fatal motor vehicle crashes in Colorado has increased dramatically since the commercialization of medical marijuana in the middle of 2009, ... full story

May 12, 2014  Underage male college students who report using marijuana in the month before they were surveyed had a high prevalence of driving under its influence and of riding with a marijuana-using driver, at a ... full story

Apr. 28, 2014  Teenagers who drink alcohol and smoke marijuana may be at increased risk for unsafe driving, according to a study. The findings point to a need for education on the risks of "simultaneous ... full story

Oct. 6, 2011  Researchers have found that drivers who test positive for marijuana or report driving within three hours of marijuana use are more than twice as likely as other drivers to be involved in motor ... full story

ScienceDaily features breaking news and videos about the latest discoveries in health, technology, the environment, and more -- from major news services and leading universities, scientific journals, and research organizations.